You never know what the weather is going to do over February and March, and if they will be out in Atlantic gales and rain without cover overhead and round the sides they will get very wet and cold. The tree will drip on them rather than provide significant cover,, the rain will probably blow in under the coop and there won't be any more room for them to shelter there than in your conservatory, even supposing they have enough sense to seek shelter there. I would strongly advise that you take them in at dusk to roost indoors for at least the next month, and allow them out only on fine dry days for an hour or two. They need to acclimatise gradually to outdoor conditions - older, fully-feathered birds that were used to those conditions would have no problems, although personally I would provide more cover and wind shelter for any of my own adult birds, let alone growers. A lot of the energy that should be going into growing new feathers and developing their bodies will be transferred to keeping warm if they are constantly wet and wind blown.
As we said earlier, raising chicks in winter isn't the easiest of tasks, and yours are now at the stage where most would be going out gradually in April- May, rather than January-February.

Another important point based on my recent experience Eirwen. They must not go straight onto long grass with empty crops. They will gorge themselves on the grass anyway and if it is long or they take too much they will crop impact or gizzard impact. Gizzard impaction is invariably fatal. You need to get the area down to less than two inches and keep them there until the novelty of grass wears off and introduce them to it after they have eaten in the morning.

Good advice as usual from Chris and Marigold, try and expose them to the outdoors as gradually as possible and keep them in at night for as long as you are able, March if it's possible. Especially liked the post about gizzard impaction which is rarely discussed. Our first experience of keeping chickens was to have a pol hybrid die 4 days after getting them, I did a post mortem and it turned out to be gizzard impaction which I think had occurred at the poultry centre where they keep their grass very long. At the time I found this article which may be helpful to anyone interested in it. http://academy.fwi.co.uk/Courses/Livest ... -impaction

In the conservatory we can give them 0.9m width x 4m length in an L shape run to sleep in, and double that to run around during the day, using an old 3ft high puppy pen. I hope this is big enough until they are are ready to go out, if they do outgrow this space before they are ready to go out (between 9-12 weeks?) I have a few options in mind about an intermediate area outside in a space in-between two outbuildings where we have a corrugated plastic roof above, so in affect a 3 sided shelter, that has a wire mesh gate covering the entire opening space which has a padlock. I am parking my car there at the mo but I don't need to, I could put their green frog coop in here with a heat source as it has a power source in the outbuildings next to it, this could be converted to be used between the ages 9-12 weeks (or longer if the weather is severe) I'm hoping as my car has never frozen under there, after that I'm hoping they'll definitely be ok to move their coop to the field where they will have a tree and an old empty caravan to shelter from any harsh weather, surrounded by a 4ft high electric fence..

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Why don't you keep them in the space between the two outbuildings for a couple of months as you suggested you could earlier in this post? This would mean that they would be fully acclimatised to the British weather when you let them out into the field.

Good article that Dinosaw. Reinforces my concerns and confirms my previous experience (which I posted a couple of months ago). I noted it mentioned that young birds coming up to lay are particularly vulnerable because of their high nutritional demands.

Thanks for all the advice everyone. It made me doubt putting them out last weekend, so I didn't. They're still in the house being pampered! Good thing is that their growth has slowed down now, so space situation won't get any worse than it already is. They are using the whole room to roam anyway, fence not much of a barrier anymore, they're good flyers! Well, some of them, the sussex and blue ranger are more squat and clumsy.
They are sounding like proper hens now, clucking away! And good thing about keeping them in with me is they're becoming more tame everyday
I know they won't be going out next wknd either, more rain and wind coming, so they'll be with me till the half term where I'll be able to put them out gradually during the week as you suggested. I'm sure by 14 weeks they'll be ok, as the breeders chicks have been out since 3 weeks ago. Also some of my pupils I teach biology to are farmers and a few of them have growers who they've put out couple of weeks ago and they're younger than mine!

We have been lucky here in North Wales with the weather, whilst it has been raining and fairly windy, it hasn't been that much worse than usual, just much warmer than it normally is this time of year.

We have started to build a shelter around the outside coop, made out of pallets, and I'll ad some plastic sheets for extra wind buffering. I'm hoping that will make life more comfortable for them.

As for the car port I had in mind, the stupid coal man went and dumped our coal there because he ran out of bags.. So that option is out for now.

Also want to mention that just around the corner from us there is a small holding with dozens of chickens that have coops in the middle of a few acres of open fields, and the only shelter they have is a few trees, and they don't have any problems, so the extra precautions we are taking I feel is just that, extra preacautions. But at least it will give me piece of mind.

Oh as to mowing the grass.. Lol, would take a while to mow the field! But I will make sure when they're out for the first time they have been fed before hand. They are loving the chick grit now anyway and I have been introducing greens in very small amounts. They are not much interested in eating yet, only playing! They regularly have games where one of them finds a 'treasure' (normally a moulted feather) and run around with it whilst the others try to grab it! Very funny to watch. There is no clear leader in the group yet, they all hold their own when challanged with the neck extended feather ruffling of one trying its luck. That's as far as it goes though, they never hurt each other for which I'm glad!

Hi all, just wanted to let you know that the not so little chicks are still with me in the conservatory, at 13 weeks now. The wind had been really bad over the last couple of weeks, glad I hadn't put them out yet. Good news is that the coop and wind shelter remained intact and in place through hurricane strength winds, so at least I can be confident that they'll be safe there!

The plan is to introduce them to the outside during the week, whilst I'm on my half term, and by the end of the week get them settled in their new home.
What I'm wondering now is- how to carry 8 of them back and forth to the field with as little stress as possible, for us and them!

Oh and I'm thinking our amber stars are actually white stars, looking at the shape of their tail. Also they're smaller and leaner and better flyers than the others! I don't mind too much as I know they'll lay a lot of nice white eggs, and they're reasonably friendly too, although not quite as laid back as I imagine the amber stars are supposed to be. They'll let me pick them up ok, and one will fly to my shoulder. But they're always the ones that have hopped the fence and are coolly strolling around the conservatory pooping everywhere! I think they spend more time out of the pen than in! Luckily I have wipeable floors!
Some of the others will hop the fence occasionally too, the only one I think that's never been is the blue ranger, she's not so great at flying bless her!